As a Light-Emitting Diode (LED) capable of issuing a visible light in red color, orange color, yellow color or yellowish green color, the compound semiconductor LED that is provided with a light-emitting layer formed of aluminum-gallium-indium phosphide ((AlXGa1-X)YIn1-YP in which 0≦X≦1 and 0<Y≦1) has been hitherto known. In the LED of this kind, the light-emitting part provided with a light-emitting layer formed of (AlXGa1-X)YIn1-YP in which 0≦X≦1 and 0<Y≦1 is generally formed on a substrate material, such as gallium arsenide (GaAs), which is optically impervious to the light emitted from the light-emitting layer and mechanically not too strong.
Recently, therefore, with a view to obtaining a visible LED of higher brightness and with the object of further enhancing the mechanical strength of the device, the technique for configuring a junction-type LED by expelling an impervious substrate material, such as GaAs, and thereafter incorporating anew a supporting layer capable of transmitting the emitted light and as well excellent in mechanical strength more than ever has been being developed (refer, for example, to Japanese Patent No. 3230638, JP-A HEI 6-302857, JP-A 2002-246640, Japanese Patent 2588849 and JP-A 2001-57441).
For the purpose of obtaining a visible LED of high brightness, the method for enhancing the efficiency of light extraction by utilizing the shape of a device has been being used. In the configuration of a device having electrodes formed respectively on the first surface and the back surface of a semiconductor light-emitting diode, the technique for effecting impartation of high brightness by utilizing the shapes of side faces has been disclosed (refer, for example, to JP-A SHO 58-34985 and U.S. Pat. No. 6,229,160).
Though the junction-type LED has made it possible to provide an LED of high brightness, the need to seek an LED of yet higher brightness is still persisting. Numerous shapes have been proposed for the devices that are so configured as to have electrodes formed respectively on the first surface and the back surface of a light-emitting diode. The device of a configuration having two electrodes formed on a surface opposite a light-extracting surface is complicated in shape and has not been optimized as respects the state of side faces and the disposition of electrodes.
This invention is directed toward the light-emitting diode provided on the surface thereof opposite the light-extracting surface with two electrodes and is aimed at providing a light-emitting diode of high brightness that exhibits a high efficiency in the extraction of light.